Now showing items 1-20 of 415

    • Application of Flow Cytometry to the Detection of Pathogenic Bacteria

      Kennedy, Deirdre; Wilkinson, Martin G. (Caister Academic Press, 2015)
      Outbreaks of infections have emphasized the necessity for rapid and economic detection methods for pathogens in samples ranging from those of clinical origin to food products during production and retail storage, and increasingly, in environmental samples. Flow cytometry (FCM) allows the rapid acquisition of multi-parametric data regarding cell populations within fluidised samples. However, the application of FCM to pathogen detection depends on the availability of specific fluorescent probes such as antibodies and RNA probes capable of detecting and isolating pathogens from these diverse samples. A particular issue for FCM methodology is the ability to recover and discriminate bacteria from the sample matrix which may pose a major technical hurdle towards accurate and sensitive analysis. This review article focuses on detection of pathogens using FCM in samples originating from food, water, environmental and clinical sources and outlines the current state of the art and potential future applications.
    • Characterisation of the Wetting Behaviour of Poor Wetting Food Powders and the Influence of Temperature and Film Formation

      Fitzpatrick, John J.; Salmon, Justine; Ji, Junfu; Miao, Song (Hosokawa Powder Technology Foundation, 2017)
      Characterisation of the wettability of five poor wetting food powders was performed using static immersion and contact angle measurements. The effect of temperature (20, 50 and 70 °C) on wettability showed varying effects on the powders. Higher temperatures majorly improved the wettability of chocolate and high fat powders but worsened the wettability of sodium caseinate and milk protein isolate. Rate-limiting regime testing was performed by pouring a fixed mass of powder on to the surface of water in an agitated beaker and visually assessing what was rate-limiting rehydration after 1 minute. The rate limiting regime tended to be floating at lower agitation speeds and dispersed clumps of varying sizes at higher speeds. However, there were major differences observed between the powders. Some of the powders formed strong films at powder/water interfaces, that could act as a barrier to water penetration and wettability. Consequently, force displacement testing was performed on a layer of powder on the water surface to assess the strength of any powder film formed. Some of the powders formed strong films that may in-part explain their poor wetting behaviour and their propensity to form strong clumps that were difficult to disrupt.
    • Preparation and Characterization of Nanoparticles Made from Co-Incubation of SOD and Glucose

      Cai, Liping; Lin, Chuntong; Yang, Nannan; Huang, Zhijie; Miao, Song; Chen, Xiaochao; Pan, Jianru; Rao, Pingfan; Liu, Shutao; National key research and development projects; et al. (Multidisciplinary Digital Publishing Institute, 2017-12-19)
      The attractive potential of natural superoxide dismutase (SOD) in the fields of medicine and functional food is limited by its short half-life in circulation and poor permeability across the cell membrane. The nanoparticle form of SOD might overcome these limitations. However, most preparative methods have disadvantages, such as complicated operation, a variety of reagents-some of them even highly toxic-and low encapsulation efficiency or low release rate. The aim of this study is to present a simple and green approach for the preparation of SOD nanoparticles (NPs) by means of co-incubation of Cu/Zn SOD with glucose. This method was designed to prepare nanoscale aggregates based on the possible inhibitory effect of Maillard reaction on heating-induced aggregation during the co-incubation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results indicated that the Maillard reaction occurred during the co-incubation process. It was found that enzymatically active NPs of Cu/Zn SOD were simultaneously generated during the reaction, with an average particle size of 175.86 ± 0.71 nm, and a Zeta potential of -17.27 ± 0.59 mV, as established by the measurement of enzymatic activity, observations using field emission scanning electron microscope, and analysis of dynamic light scattering, respectively. The preparative conditions for the SOD NPs were optimized by response surface design to increase SOD activity 20.43 fold. These SOD NPs showed storage stability for 25 days and better cell uptake efficacy than natural SOD. Therefore, these NPs of SOD are expected to be a potential drug candidate or functional food factor. To our knowledge, this is the first report on the preparation of nanoparticles possessing the bioactivity of the graft component protein, using the simple and green approach of co-incubation with glucose, which occurs frequently in the food industry during thermal processing.
    • Preliminary characterization of a novel β-agarase from Thalassospira profundimonas

      Zeng, Cheng; Zhang, Longtao; Miao, Song; Zhang, Yi; Zeng, Shaoxiao; Zheng, Baodong; Regional Demonstration of Marine Economy Innovative Development Project; the Science and Technology Plan of Fujian Province; China Scholarship for Visiting Scholar; 12PYY001SF08; et al. (Springer Science and Business Media LLC, 2016-07-15)
      Background The objective of this study was to characterize the agarase from a newly isolated agarolytic bacterium Thalassospira profundimaris fst-13007. Results Agarase-fst was purified to homogeneity which apparent molecular weight was 66.2 kDa. Its activity was optimal at 45 °C and pH 8 and was stable at pH 5–9 or 30–50 °C. Agarase-fst required Mn2+ for agarase activity and inhibition by Cu2+, Fe3+ and EDTA. Tests of hydrolysis pattern and substrate specificity, TLC analysis and mass spectrometry of the hydrolysis products revealed that it is an endo-type β-agarase hydrolyzing agarose into neoagarobiose, neoagarotetraose and neoagarohexaose. Results of MALDI-TOF-TOF/MS indicate that it lack of homology to previously identified proteins and present conserved domain of β-agarase. Conclusion Agarase-fst from T. profundimaris fst-13007 was confirmed to be a novel endo-type β-agarase.
    • Increases of Lipophilic Antioxidants and Anticancer Activity of Coix Seed Fermented by Monascus purpureus

      Zeng, Haiying; Qin, Likang; Liu, Xiaoyan; Miao, Song; Natural Science Foundation of Guizhou Province; Agriculture Committee of Guizhou Province; grant number (2019) 1111; grant number (2017) 106 & (2018) 81 (Multidisciplinary Digital Publishing Institute, 2021-03-09)
      Lipophilic tocols, γ-oryzanol, and coixenolide in coix seed before and after fermentation by Monascus purpureus were determined. Antioxidant and anticancer activities of raw and fermented coix seed were evaluated using free-radical-scavenging assays and polyunsaturated fatty acid oxidation model, and human laryngeal carcinoma cell HEp2, respectively. Compared to the raw seed, the tocols, γ-oryzanol, and coixenolide contents increased approximately 4, 25, and 2 times, respectively, in the fermented coix seed. Especially, γ-tocotrienol and γ-oryzanol reached 72.5 and 655.0 μg/g in the fermented coix seed. The lipophilic extract from fermented coix seed exhibited higher antioxidant activity in scavenging free radicals and inhibiting lipid oxidation. The inhibitory concentrations for 50% cell survival (IC50) of lipophilic extract from fermented coix seed in inhibiting HEp2 cells decreased by 42%. This study showed that coix seed fermented by M. purpureus increased free and readily bioavailable lipophilic antioxidants and anticancer activity. Therefore, fermentation could enhance the efficacy of the health promoting function of coix seeds.
    • Influence of pre-crystallisation and water plasticization on flow properties of lactose/WPI solids systems

      Li, Runjing; Roos, Yrjö H.; Miao, Song; Department of Agriculture, Food and Marine, Ireland; 11-F-001 (Elsevier, 2016-06)
      This study investigated the influence of pre-crystallisation and water plasticization on flow properties of lactose/whey protein isolate (WPI) solids systems. Powder characteristics of lactose/WPI mixtures with different amounts of α-lactose monohydrate (1.01%, 11.18%, 29.20%, and 46.84%, w/w) were studied. Dairy powders with higher amounts of crystalline lactose showed larger tapped bulk density and particle density. Morphological characteristic study indicated that dairy solids with higher crystallinity had less rounded shape and rougher surface. Increasing protein content or crystalline lactose content could decrease the molecular mobility of dairy solids. Flow function tests indicated that dairy solid with 11.18% crystallinity was more easy-flowing than lactose/WPI mixtures with 1.01%, 29.20% and 46.84% crystallinity at 0% and 44% relative humidity (RH) storage conditions. Furthermore, dairy solids with higher amount of crystalline lactose showed better resistance to develop cohesive at high RH storage conditions. The friction angle of dairy solid with 1.01% crystallinity increased with increasing water content, while friction angles of lactose/WPI mixtures with higher crystallinity decreased with increasing water content.
    • Applications of ultrasound to enhance fluidized bed drying of Ascophyllum Nodosum: Drying kinetics and product quality assessment

      Zhu, Xianglu; Zhang, Zhihang; Hinds, Laura M.; Sun, Da-Wen; Tiwari, Brijesh K.; UCD-CSC Scholarship Scheme supported by University College Dublin (UCD) and China Scholarship Council (CSC) (Elsevier, 2021-01)
      In this study, ultrasound either as a pretreatment technique or as an integrated technique was employed to enhance fluidized bed drying of Ascophyllum nodosum, and drying kinetics and dried product quality were assessed. In order to compare technology efficiency and dried product qualities, oven drying and fluidized bed drying (FBD) were employed. The novel drying methods included airborne ultrasound-assisted fluidized bed drying (AUA), ultrasound pre-treatment followed by FBD (USP), and hot water blanching pre-treatment followed byFBD (HWB). Six drying kinetics models were used to describe the drying curves, among which the Page model was the best in fitting USP and AUA. Model by Millidi et al. was employed to describe HWB. Airborne ultrasound in AUA did not reduce energy consumption or drying time, but retained total phenolic content (TPC) as well as colour, and exhibited the highest yield among the novel drying methods. USP and HWB showed lower energy consumption and drying time considerably, but the TPC was the lowest among the studied methods. At the same time, USP dried product exhibited the lowest aw, followed by HWB and then AUA. This studyalso demonstrated that FBD could be a very practical drying method on Irish brown seaweed, and ultrasound-assisted drying methods may have potential developments in Irish brown seaweed drying process.
    • Dynamic adsorption and interfacial rheology of whey protein isolate at oil-water interfaces: Effects of protein concentration, pH and heat treatment

      Zhou, Beibei; Tobin, John T.; Drusch, Stephan; Hogan, Sean A.; Department of Agriculture, Food and Marine; Teagasc Walsh Fellow Scheme; 2017122 (Elsevier, 2021-07)
      The effects of bulk protein concentration, Cp, (0.01, 0.1, 1 wt%), pH (3, 4.7 and 7) and heat treatment (unheated or 95 °C for 30 min) on whey protein isolate (WPI) stabilized interfaces were examined. The interfacial pressure and shear rheology of WPI-stabilized sunflower oil-water (o/w) interfaces were characterized using a pendant drop tensiometer and a rheometer equipped with a Du Nöuy ring. The rate of WPI adsorption was faster at higer Cp and pH 3. Heat-enhanced surface activity was more pronounced at pH 7 compared to pH 3 as a result of greater heat stability of WPI at acidic pH. The elastic modulus of WPI stabilized interfaces increased with Cp (≤0.1 wt%). A further increase in Cp (to 1 wt%) resulted in monolayer collapse and weaker films. Non-heated (NHT) WPI formed less elastic interfacial films at pH 3 than at pH7. Heat treatment enhanced the elastic behavior of interfacial films with longer relaxation times. This may be associated with the formation of intermolecular β-sheets. The knowledge gained on the nature of WPI-stabilized interfaces can be used to better understand the stability of dairy emulsions during subsequent processing, digestion or storage.
    • Combined effects of ultrasound, plasma-activated water, and peracetic acid on decontamination of mackerel fillets

      Zhao, Yi-Ming; Oliveira, Marcia; Burgess, Catherine M.; Cropotova, Janna; Rustad, Turid; Sun, Da-Wen; Tiwari, Brijesh K.; UCD-CSC Scholarship provided by University College Dublin (UCD) and China Scholarship Council (CSC); JPI project ProHealth; 15/HDHL/1 PROHEALTH (Elsevier, 2021-10)
      It is usually quite challenging to rely on one single intervention to achieve a satisfactory antimicrobial effect and maintain quality attributes of food. This study aimed to investigate the decontamination effectiveness of individual treatments, including ultrasound (US), plasma-activated water (PAW), and peracetic acid (PAA) and their combinations against native microbiota (total mesophilic bacteria (TMC) and total psychrotrophic bacteria (TPC)) and inoculated bacteria (Escherichia coli, Listeria innocua, and Pseudomonas fluorescens) on raw mackerel fillets. The impacts of the treatments on fish quality characteristics, such as colour, and lipid oxidation (primary and secondary products) were determined. Meanwhile, the physicochemical properties of PAW and plasma-activated PAA (PA-PAA), including pH, oxidation-reduction potential (ORP), conductivity, and reactive oxygen nitrogen species (RONS) after plasma treatment were examined. The results showed that combined treatments involving PAA tended to achieve higher inactivation rates, with the greatest inactivation of 0.72, 0.62, and 0.5 log CFU/g for L. innocua, E. coli, and P. fluorescens respectively. Significantly higher values of RONS and more acidic pH in PA-PAA were observed than that in PAW or PAA (P ≤ 0.05), demonstrating the synergistic effect of the hurdle interventions, though the inactivation rates on the fish samples were not significantly higher than the individual treatments. Fish quality parameters were not notably affected compared to the control. The study showed promising results for fish decontamination, offering potential alternative options for future application.
    • In the quest of the optimal chondrichthyan for the development of collagen sponges for articular cartilage

      Wu, Z.; Korntner, S.H.; Mullen, A.M.; Zeugolis, D.I.; Teagasc Walsh Fellowship; Department of Agriculture, Food and the Marine; Science Foundation Ireland; European Regional Development Fund (ERDF); European Research Council (ERC); 2014045; et al. (Elsevier, 2021-09)
      The limited capability of articular cartilage to self-repair renders its regeneration a formidable challenge. In the quest of the optimal material for cartilage scaffold fabrication, the use of collagen type II has been advocated, but its optimal source still remains elusive. Herein, the potential of four [lesser spotted dogfish (Scyliorhinus canicula), thorn back ray (Raja clavata), cuckoo ray (Leucoraja naevus) and blonde ray (Raja brachyuran)] cartilaginous fish (chondrichthyes) derived collagen type II preparation in cartilage engineering was assessed. Collagen type II was extracted using the acid-pepsin method, crosslinked with 4-arm poly (ethylene glycol) succinimidyl glutarate sponges were fabricated and their biophysical, biochemical and biological properties were assessed. Pure collagen type II preparations were obtained from all four chondrichthyes, as revealed by gel electrophoresis. Pore size, porosity, mechanical properties, denaturation temperature, free amine content and resistance to enzymatic degradation of the produced sponges were not significantly (p > 0.05) affected as a function of species. Biological analysis using human adipose derived stem cells revealed no significant (p > 0.05) differences between the groups in cell viability, DNA concentration, metabolic activity, Alcian blue staining and sulphated glycosaminoglycans synthesis. Human adipose derived stem cells seeded on fish-derived scaffolds expressed lower mRNA levels of COL1A1 (fold change ≥ 2.0) and COL3A1 (apart from lesser spotted dogfish; fold change < 2.0) and higher mRNA levels of COL10A1 (fold change ≥ 2.0), COMP (fold change ≥ 2.0), SOX9 (fold change ≥ 2.0), and ACAN (apart from cuckoo ray; fold change < 2.0) than cells grown on tissue culture plastic. Our data suggest that chondrichthyes derived collagen type II has the potential to be used in cartilage engineering.
    • Development of chemometric models using Vis-NIR and Raman spectral data fusion for assessment of infant formula storage temperature and time

      Wang, Xiao; Esquerre, Carlos; Downey, Gerard; Henihan, Lisa; O'Callaghan, Donal; O'Donnell, Colm; Irish Department of Agriculture, Food and the Marine; 11/F/052 (Elsevier, 2021-01)
      This study evaluated the potential of Vis-NIR and Raman spectral data fusion combined with PLS and SVM chemometric models developed using a large dataset (n = 1700) of commercial infant formula (IF) samples to (i) discriminate between different IF storage temperature (20, 37 °C) and (ii) predict IF storage time (0–12 months). Three interval-based PLS variable selection methods (forward interval PLS (FiPLS), backward interval PLS (BiPLS) and synergy interval PLS (SiPLS)) and SVM-recursive feature elimination (SVM-RFE) methods were compared for model development. The best IF storage temperature discrimination model was developed using SVM classification (SVMC) and Vis-NIR spectra (400–2498 nm) (AccuracyCV = 99.82%, AccuracyP = 100%). SVM regression (SVMR) models developed using medium level data fusion (features selected by SVM-RFE) had the lowest root mean square error (RMSE) values for IF samples stored at either temperature, 20 °C or 37 °C (RMSECV = 0.7–0.8, RMSEP = 0.6–0.9). Industrial relevance Spectroscopic technologies, including Vis-NIR and Raman spectroscopy have been widely applied for process analysis and increasingly for on-line process monitoring in areas of chemicals, food processing, agriculture and pharmaceuticals, etc. Due to their rapid measurement and minimal or no sample preparation, they are highly suitable for in-line process monitoring. This study demonstrates that Vis-NIR and Raman process analytical tools either individually or combined may be employed for quality assessment and process control of IF manufacture.
    • Evaluation of rennet-induced gelation under different conditions as a potential method for 3D food printing of dairy-based high-protein formulations

      Uribe-Alvarez, Ricardo; O'Shea, Norah; Murphy, Craig P.; Coleman-Vaughan, Caroline; Guinee, Timothy P.; Department of Agriculture, Food and the Marine; Walsh Scholarship programme; 17/F/246 (Elsevier, 2021-05)
      The rennet-induced gelation of milk proteins was evaluated as a potential method for the formation of 3D printed food structures. The effects of pH, [Ca2+], and temperature on the rennet gelation properties of milk protein dispersion with 15% (w/w) protein content were assessed using low amplitude strain oscillation rheometry. A cycled-temperature ramp (heating-holding-cooling) during rheological measurements was suitable to evaluate gel firmness development, as an imitation of the temperature profile in the 3D printing process. A factorial design considering two levels of pH (6.0 and 6.4), [Ca2+] (1.5 and 5.7 mM), and temperature (31 and 40 °C), showed that the pH, temperature, and its interaction were the main factors enhancing gel formation and the strength of the resultant gel. At pH 6.0 and temperature ramped to 40 °C followed by cooling to 15 °C, a very high gel strength (~8–9 kPa) was obtained. These results showed that rennet-induced gelation could be manipulated for developing printable dairy formulations.
    • Application of a LED-UV based light technology for decontamination of chicken breast fillets: Impact on microbiota and quality attributes

      Soro, Arturo B.; Whyte, Paul; Bolton, Declan J.; Tiwari, Brijesh K.; Department of Agriculture, Food, and Marine (DAFM); Teagasc Walsh Fellowship; DAFM/17/F/275 (Elsevier, 2021-06)
      Light-emitting diode (LED) technologies are economical and efficient devices that could be considered in poultry processing as disinfection strategies. This study evaluated the efficacy of a LED-based device to reduce the microbial load on chicken meat and investigated it's impact on selected quality parameters. Quality parameters including pH, texture and color after LED-UV exposure and during subsequent storage for 7 days at 4 ̊C were investigated. Diced chicken breast fillets were exposed to UV light wavelengths of 255, 280, 300 and 365 nm for 2, 4, 6, 8 and 10 min. A microbiological analysis was conducted on chicken samples to enumerate bacterial counts. Reductions between 1.17 and 1.67 log CFU/g for total viable counts of mesophilic, psychrophilic bacteria and total Enterobacteriaceae counts were observed, whereas, up to 2 log CFU/g was obtained for Pseudomonas and lactic acid bacteria groups after treatment with wavelengths of 280, 300 and 365 nm. Furthermore, color, texture and pH were not affected by exposure to UV light at 280 nm even following 7 days storage. Thus, LED-based technologies could be applied on poultry meat to reduce the levels of spoilage bacteria while maintaining quality attributes.
    • Ultrasound Assisted Modulation of Yeast Growth and Inactivation Kinetics

      Soro, Arturo B.; Oliveira, Marcia; O'Donnell, Colm P.; Tiwari, Brijesh K; Teagasc Walsh Fellowship program; Department of Agriculture, Food, and Marine (DAFM); DAFM/17/F/275 (Elsevier, 2021)
      The yeast Saccharomyces cerevisiae is well known for its application in the food industry for the purpose of developing fermented food. The ultrasound (US) technology offer a wide range of applications for the food industry, including the enhancement of fermentation rates and inactivation of microbial cells. However, a better understanding and standardization of this technology is still required to ensure the scaling-up process. This study investigated the effect of the US technology on the growth of S. cerevisiae using frequencies of 20, 25, 45 and 130 kHz, treatment periods from 2 to 30 min. Furthermore, yeast kinetics subjected to US treatments were evaluated using modelling tools and scanning electron microscopy (SEM) analysis to explore the impact of sonication on yeast cells. Yeast growth was monitored after different US treatments plotting optical density (OD) at 660 nm for 24 h at 30 ⁰C. Growth curves were fitted using models of modified Gompertz and Scale-Free which showed good parameters of the fit. In particular, US frequencies of 45 and 130 kHz did not have a disruptive effect in lag phase and growth rate of the yeast populations, unlike the frequency of 20 kHz. Moreover, inactivation curves of yeast cells obtained after exposure to 20 and 25 kHz also observed the best fit using the Weibull model. US frequency of 20 kHz achieved significant reductions of 1.3 log cfu/mL in yeast concentration and also induced important cell damage on the external structures of S. cerevisiae. In conclusion, the present study demonstrated the significant effect of applying different US frequencies on the yeast growth for potential application in the food industry.
    • Selective and sensitive UHPLC-ESI-Orbitrap MS method to quantify protein oxidation markers

      Poojary, Mahesha M.; Tiwari, Brijesh K.; Lund, Marianne N.; Independent Research Fund Denmark; Science Foundation Ireland; 7017-00133B; 17/CDA/4653 (Elsevier, 2021-11)
      A targeted UHPLC-MS/MS isotopic dilution method has been developed for the simultaneous quantification of 18 different free and protein-bound aromatic amino acid oxidation products in food and biological matrices. All analytes, including critical isomeric pairs of Tyr, o-Tyr, m-Tyr, and dioxyindolylalanine diastereomers were chromatographically resolved to obtain high selectivity, without the need for derivatizing or ion pairing agents. The results of method validation showed adequate retention time reproducibility [0.1–0.6% coefficient of variation (CV) for over 224 injections], accuracy (within ±1–20% of the nominal concentration), and precision (1–17% CV) for all target analytes. The lower limit of quantification was calculated in different matrices using both the Hubaux-Vos approach and accuracy and precision data showing values in the range of 0.2–15 ng/mL. Use of stable isotope-labelled internal standards compensated errors due to matrix effects and artefactual degradation of analytes. Both acid and enzymatic hydrolyses were tested to obtain the best possible results for the quantification of protein oxidation products, demonstrating the stability of target analytes under hydrolytic conditions. The method was successfully applied to quantify target analytes in serum, tissue, milk, infant formula, pork liver pâté, chicken meat and fish. The method was also applied to assess the role of Fenton's reagent in oxidizing Trp, Phe and Tyr residues in different proteins, with results showing o-Tyr, dioxyindolylalanine diastereomers, kynurenine, dityrosine being the main oxidation products. The Fenton chemistry favored the formation of o-Tyr over m-Tyr from Phe with 2–36 folds higher yields. 3-Nitrotyrosine, a marker of protein nitration, was also detected in samples treated with Fenton's reagent.
    • Understanding preferences for and consumer behavior toward cheese among a cohort of young, educated, internationally mobile Chinese consumers

      Ouyang, Hao; Li, Bozhao; McCarthy, Mary; Miao, Song; Kilcawley, Kieran; Fenelon, Mark; Kelly, Alan; Sheehan, Jeremiah J.; Teagasc Walsh Scholarship; Dairy Levy Trust Fund; et al. (Elsevier, 2021-12)
      This study explores the experiences of a cohort of young, educated, internationally mobile Chinese consumers with cheese and other dairy products, and how these experiences shape their behavior toward cheese products. In total, 41 Chinese students studying at an Irish university participated in 5 focus groups (n = 41, n = 7–10). Thematic analysis identified important factors that influence consumer behaviors regarding cheese products. Individuals' expectations toward cheese were embedded in their knowledge structures, which were constructed from previous experience. Participants had general positive expectations toward cheese due to associations with western-style foods and nostalgia; however, direct eating experience determined long-term behavior. When making a purchase decision, choice motives were weighed and negotiated to establish a fundamental driving factor for purchase. Perceived probability of choice motive fulfillment was important in determining purchase decisions, with many participants having low perceived ability to select cheese and limited motivation to engage with cheese due to limited perceived relevance of cheese to their daily food life. Individuals' innovativeness was an important factor that influences their openness to cheese products when moving beyond familiar foods. Opportunities exist such as using nostalgic cues as marketing tools to increase consumers' interest in cheese or combining cheese with Chinese food to increase perceived relevance of cheese to their daily food life. Providing information at point of purchase could reduce the disconnect between expectation and actual experience, and innovative cheese products may be developed to better fulfill important choice motives.
    • The bovine colostrum and milk metabolome at the onset of lactation as determined by 1H-NMR

      O'Callaghan, Tom F.; O'Donovan, Michael; Murphy, John Paul; Sugrue, Katie; Tobin, John T.; McNamara, Aoife E.; Yin, Xiaofei; Sundaramoorthy, Geetha; Brennan, Lorraine; Teagasc (Elsevier, 2021-02)
      The purpose of this study was to characterise the metabolome of bovine colostrum and milk in the initial days of lactation. Colostrum and milk samples were collected from 18 cows representing an even spread of 1st, 2nd and 3rd lactation (n = 6) over the first 6 days of lactation. Samples were subsequently analysed using 1H-NMR. The metabolome of defatted colostrum and milk in the days immediately post parturition was demonstrated to be complex and changed significantly over time. The colostrum was rich in nutrients beneficial for growth and development of the new-born mammal with significantly higher levels of essential branched chain amino acids and choline and orotic acid that decreased in the subsequent days as milk composition evolved to that of regular milk. Multivariate analysis of metabolome profiles using PLS-DA was demonstrated to clearly distinguish between colostrum and subsequent milk samples.
    • Strategies to enhance the rehydration performance of micellar casein-dominant dairy powders

      McSweeney, David J.; O'Mahony, James A.; McCarthy, Noel A.; Irish Department of Agriculture, Food and the Marine; 15-F-679 (Elsevier, 2021-11)
      Due to their excellent nutritional (e.g., high calcium) and functional (e.g., heat stability and gelation) properties, the use of protein-enriched, micellar casein-dominant dairy powders, including milk protein concentrate/isolate and micellar casein concentrate, has increased considerably among food and beverage manufacturers. However, the poor and often inconsistent rehydration properties of these powders in water, specifically their low dispersibility and solubility (attributed to protein–protein interactions related to the high proportion of micellar casein), remains a significant challenge. This review provides a detailed analysis of the main physical (e.g., injection of gas, ultrasonication) and chemical (e.g., ion exchange, pH adjustment) processing strategies that have been applied, at both laboratory and pilot-scale, to enhance the rehydration performance of high-protein, micellar casein-dominant dairy powders. The information provided will support the advancement of dairy ingredient research and the technological development of nutritional powders that can be used across several industrial applications.
    • Heat induced inactivation of microorganisms in milk and dairy products

      Lindsay, D.; Robertson, R.; Fraser, R.; Engstrom, S.; Jordan, K. (Elsevier, 2021-10)
      It is well understood that heat treatment of milk, such as pasteurisation, allows its safe consumption in terms of foodborne illness, while failure in adequate heat treatment has resulted in both product recalls and also foodborne disease outbreaks. Aspects of different heat treatments within the dairy industry that affect relevant microorganisms, with an emphasis on bacteria, are discussed in this review. These include a description of D- and Z-values as measures of heat resistance, the factors that affect D-values, such as different dairy matrices, a discussion of some of the mechanisms associated with heat resistance of bacteria important for dairy products, different types of heating effects on microorganisms present in various dairy products, and recommendations for the most appropriate experimental design for understanding how heat affects microorganisms.
    • Assessment of the response of indigenous microflora and inoculated Bacillus licheniformis endospores in reconstituted skim milk to microwave and conventional heating systems by flow cytometry

      Li, F.; Santillan-Urquiza, E.; Cronin, U.; O'Meara, E.; McCarthy, W.; Hogan, S.A.; Wilkinson, M.G.; Tobin, J.T.; Department of Agriculture, Food and the Marine; Enterprise Ireland; et al. (Elsevier, 2021-09)
      Heat treatment is one of the most widely used processing technologies in the dairy industry. Its primary purpose is to destroy microorganisms, both pathogenic and spoilage, to ensure the product is safe and has a reasonable shelf life. In this study microwave volumetric heating (MVH) was compared with a conventional tubular heat exchanger (THE), in terms of the effects of each at a range of temperatures (75°C, 85°C, 95°C, 105°C, 115°C, and 125°C) on indigenous microflora viability and the germination of inoculated Bacillus licheniformis endospores in reconstituted skim milk. To assess the heat treatment–related effects on microbial viability, classical agar-based tests were applied to obtain the counts of 4 various microbiological groups including total bacterial, thermophilic bacterial, mesophilic aerobic bacterial endospore, and thermophilic aerobic bacterial endospore counts, and additional novel insights into cell permeability and spore germination profiles post-heat treatment were obtained using real-time flow cytometry (FC) methods. No significant differences in the plate counts of the indigenous microorganisms tested, the plate counts of the inoculated B. licheniformis, or the relative percentage of germinating endospores were observed between MVH- and THE-treated samples, at equal temperatures in the range specified above, indicating that both methods inactivated inoculated endospores to a similar degree (up to 70% as measured by FC and 5 log reduction as measured by plate counting for some treatments of inoculated endospores). Furthermore, increased cell permeability of indigenous microflora was observed by FC after MVH compared with THE treatment of uninoculated skim milk, which was reflected in lower total bacterial count at a treatment temperature of 105°C. This work demonstrates the utility of FC as a rapid method for assessing cell viability and spore inactivation for postthermal processing in dairy products and overall provides evidence that MVH is at least as effective at eliminating native microflora and inoculated B. licheniformis endospores as THE.